Gowther is welcomed by the others into their group, but he soon finds out the true secrets behind them by delving deep into their memories and emotions. Meanwhile, Hendrickson and Helbram have the hilt of Meliodas's sword in possession, in which they plan to use it as a fragment of a ritual relic, known as the Coffin of Eternal Darkness, to resurrect the red demon race as a means to start a holy war. At the Boar Hat, Holy Knight Vivian suddenly appears and kidnaps Elizabeth and Hawk. Diane throws Meliodas, Ban and Gowther toward the Kingdom of Liones, where the three are bombarded by an army of Holy Knights on the north side of the castle. However, Arthur Pendragon, the young king of Camelot, has approached the south side of the castle with his own army.

Hendrickson tries to convince Arthur to leave the castle, but to no avail. Instead, Hendrickson escorts Arthur inside the castle and suddenly engages him in battle. Meanwhile, Elizabeth and Hawk are teleported inside the dungeon of the castle, and they try to find a way out. Meliodas, Ban and Gowther manage to defeat the army and sneak inside a town of the kingdom, while King summons his black hound Oslow to use its mouth to teleport Diane inside the castle. However, Diane is attacked by Guila, Jericho, Gilthunder, Howzer, Helbram and Great Holy Knight Dreyfus. Diane tries to defend herself, but Dreyfus overpowers her with an attack that sends her crashing onto the town streets. After Diane wander the streets and protects Zeal from being crushed by a falling building, both Howzer and Guila switch sides to defend Diane.

The combined powers of Howzer and Guila have little to no effect. When Dreyfus attacks Guila, Gowther saves Guila in the nick of time and faces Dreyfus alone. Meanwhile, Elizabeth and Hawk encounter Margaret Liones, Elizabeth's eldest sister, in a cell. Vivian appears, teleporting Hawk elsewhere, knocking Elizabeth unconscious and releasing Margaret from her cell. Gowther traps Dreyfus in a nightmare, but Dreyfus somehow snaps out of it and pierces Gowther in the chest. Once a heavily injured Dreyfus leaves with Gilthunder, Helbram attempts to finish Diane off, but King appears and stops Helbram, who reveals himself as a fairy and King's former best friend. Helbram uses his magical tree roots to restrain King and inflict brutal lashes on Diane. However, King uses Chastifol to shield Diane from getting hurt. King says that he is fulfilling a promise that he made seven hundred years ago.

Gilthunder leaves Dreyfus to fight Meliodas alone, while Hendrickson deals with Arthur and ultimately defeats him. Meanwhile, Elizabeth wakes up in a chamber and finds her father, King Bartra Liones. Meliodas then finds himself outmatched against Gilthunder, Hendrickson and Vivian. At the same time, Margaret decides to take her own life by jumping off a castle tower. Margaret and Gilthunder are both released from their curse in the form of monsters, thanks to Meliodas. While Margaret is thus saved from falling, Hendrickson tries to finish Meliodas off, but Gilthunder stands in the way and knocks down Hendrickson at full force. Vivian tries to trap Meliodas, Gilthunder, Margaret and Arthur in illusionary places, but Merlin, the Boar's Sin of Gluttony, makes her first appearance and breaks the spell.

Ban explores the catacombs under the city. Merlin and the other sins go to the chamber where the king Baltra and Elizabeth are being held captive. Dreyfus has a confession.

Ban attempts to kill Meliodas, but is stopped by Hawk. Meliodas and the sins corner Hendriksen and prepare to take him down.

Business at the Boar Hat is dropping, so Meliodas asks Merlin to join the staff as a waitress alongside Elizabeth and Diane to attract customers.